The use of gravel pack assemblies and fracture pack assemblies are well known to those skilled within the art and such assemblies are widely used in oil and gas well completion operations.
Fracture packing assemblies are generally used to stimulate well production by using liquids pumped down a well-bore under pressure to fracture the rock formations adjacent to the well-bore. In some operations, such as hydraulic fracturing, these operations utilize various agents suspended within the liquid to keep the formation fractures open, thereby inducing an increase in flow rates of gas or oil from the formation into the well-bore. Gravel pack completion operations are generally used for controlling the sand in unconsolidated reservoirs. Gravel packs may also be used in open-hole completions or inside-casing applications. One example of a typical gravel pack application involves reaming a cavity in the well-bore and then filling the reamed area with loose sand. This process, referred to as gravel pack, provides a consolidated sand layer in the well-bore adjacent the surrounding oil or gas producing formation, thereby restricting sand migration from the formation. A slotted or screen liner is deployed within the formed gravel pack, thereby allowing the oil and gas production fluids to enter the production tubing flowing to the surface while filtering out the surrounding gravel.
A more specialized operation utilizes high-pressure fluids to pack or squeeze the carrier fluid into the formation, thereby placing gravel in perforations of a completed well and into the space around and between the sand screens and the formation.
Fracture packing operations are very similar to the above gravel packing and operation, except the pumping operation is performed using higher pressures and with a denser, viscous fluid in order to fracture rock formations, thus creating perforations and tunnels. Therefore, the down-hole tool assemblies used for the two procedures are generally the same.
Gravel pack or fracture pack assemblies are run into the well-bore on what is referred to as a work string consisting of a length of drill pipe normally removed from the well-bore when the pumping operation is complete. The completion assemblies also contain a setting tool for the packer assembly being used and a crossover or flow diversion valve assembly used to redirect the high-pressure fluids into the formation. Such assemblies generally require a setting ball to be dropped from the surface which must fall to a seat located within the packer assembly, thereby actuating the packer and thus isolating the packer assembly from the upper portion of the well-bore. In some cases, the ball establishes the crossover flow path in the packer as well. Various drawbacks plague this type of operation, such as the ball being lost or damaged, or seat damage and/or debris may also cause seating problems. Further, it takes quite some time for the ball to reach the completion assembly. Most importantly, the setting and crossover tools must be pulled from the well-bore before the seal assembly and production tubing can be run into the well-bore. When the pumping operation is completed, the entire work string is commonly removed from the well and a separate production string, through which the production fluids or gases will flow, is then landed back in the reservoir. Replacement of the work string with the production string takes considerable rig time and adds to the expense of the completion. It is commonly understood that the withdrawal and run in operation exposes the well to fluid losses and often results in formation damage.
A need exists, therefore, for a gravel pack, fracture pack, and like assembly systems that can be run into the well that would eliminate the various problems that plague current systems, greatly increasing the potential successfulness and life of the gravel or fracture pack and saving considerable rig time.